blob: efad8dcf902877f4b67e5179dbd1dc17ba695abb (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
/*
* linux/drivers/devfreq/governor_simpleondemand.c
*
* Copyright (C) 2011 Samsung Electronics
* MyungJoo Ham <myungjoo.ham@samsung.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/errno.h>
#include <linux/devfreq.h>
#include <linux/math64.h>
/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
#define DFSO_UPTHRESHOLD (90)
#define DFSO_DOWNDIFFERENCTIAL (5)
static int devfreq_simple_ondemand_func(struct devfreq *df,
unsigned long *freq)
{
struct devfreq_dev_status stat;
int err = df->profile->get_dev_status(df->dev.parent, &stat);
unsigned long long a, b;
unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
struct devfreq_simple_ondemand_data *data = df->data;
if (err)
return err;
if (data) {
if (data->upthreshold)
dfso_upthreshold = data->upthreshold;
if (data->downdifferential)
dfso_downdifferential = data->downdifferential;
}
if (dfso_upthreshold > 100 ||
dfso_upthreshold < dfso_downdifferential)
return -EINVAL;
/* Assume MAX if it is going to be divided by zero */
if (stat.total_time == 0) {
*freq = UINT_MAX;
return 0;
}
/* Prevent overflow */
if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) {
stat.busy_time >>= 7;
stat.total_time >>= 7;
}
/* Set MAX if it's busy enough */
if (stat.busy_time * 100 >
stat.total_time * dfso_upthreshold) {
*freq = UINT_MAX;
return 0;
}
/* Set MAX if we do not know the initial frequency */
if (stat.current_frequency == 0) {
*freq = UINT_MAX;
return 0;
}
/* Keep the current frequency */
if (stat.busy_time * 100 >
stat.total_time * (dfso_upthreshold - dfso_downdifferential)) {
*freq = stat.current_frequency;
return 0;
}
/* Set the desired frequency based on the load */
a = stat.busy_time;
a *= stat.current_frequency;
b = div_u64(a, stat.total_time);
b *= 100;
b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
*freq = (unsigned long) b;
return 0;
}
const struct devfreq_governor devfreq_simple_ondemand = {
.name = "simple_ondemand",
.get_target_freq = devfreq_simple_ondemand_func,
};
|
